process: signal PTY foreground group

.github/workflows/ci.yml

@@ -110,6 +110,7 @@ jobs:
   m6-perf-gates:
     name: M6 Perf Gates
     runs-on: ubuntu-latest
+    timeout-minutes: 15
     steps:
       - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@stable

src/process.rs

@@ -507,6 +507,21 @@ impl ChildHandle {
     }
 }
 
+fn signal_target(proc: &ManagedProcess, pid: u32) -> Result<Pid, String> {
+    if let Some(runtime) = proc.runtime.as_ref()
+        && let ChildHandle::Pty {
+            _master: master, ..
+        } = &runtime.child
+        && let Some(pgrp) = master.process_group_leader()
+        && pgrp > 0
+    {
+        return Ok(Pid::from_raw(-pgrp));
+    }
+    Ok(Pid::from_raw(
+        i32::try_from(pid).map_err(|e| e.to_string())?,
+    ))
+}
+
 /// Termination status of one generation. Internal --- the supervisor
 /// translates this into a [`Termination`] with timing.
 enum TermStatus {
@@ -673,8 +688,10 @@ impl ProcessSupervisor {
     }
 
     /// Send `signal` to `id`. Errors if the id is unknown or the
-    /// process is not currently running. The signal is applied to
-    /// the OS pid via [`nix::sys::signal::kill`]; nothing about the
+    /// process is not currently running. Pipe-mode children are
+    /// signaled by OS pid; PTY-mode children are signaled via the
+    /// foreground process group when the kernel reports one, matching
+    /// terminal C-c behavior for shells and REPLs. Nothing about the
     /// supervisor's state changes synchronously --- the lifecycle
     /// transition happens when the supervisor next observes the
     /// child's exit through `tick`.
@@ -687,8 +704,8 @@ impl ProcessSupervisor {
         else {
             return Err(format!("process {id} is not running"));
         };
-        let nix_pid = Pid::from_raw(i32::try_from(pid).map_err(|e| e.to_string())?);
-        nix::sys::signal::kill(nix_pid, Some(signal)).map_err(|e| format!("kill: {e}"))?;
+        let target = signal_target(proc, pid)?;
+        nix::sys::signal::kill(target, Some(signal)).map_err(|e| format!("kill: {e}"))?;
         if matches!(signal, Signal::SIGTERM | Signal::SIGKILL | Signal::SIGHUP) {
             proc.state = ProcessState::Exiting {
                 pid,

tests/m6_5_repl_acceptance.rs

@@ -273,7 +273,7 @@ fn m6_5_ctrl_d_on_nonempty_input_deletes_char_forward() {
     "#);
 }
 
-/// Acceptance bullet 3: C-c sends SIGINT. We spawn `cat` (which
+/// Acceptance bullet 3: C-c sends SIGINT. We spawn `sleep` (which
 /// terminates on SIGINT) and verify the exit marker reports the
 /// expected signal. The signal name in the marker is symbolic
 /// ("SIGINT") rather than a number, per the M6.5 design (the libc
@@ -285,12 +285,20 @@ fn m6_5_ctrl_d_on_nonempty_input_deletes_char_forward() {
 /// profile under `cargo test`'s default parallelism).
 #[test]
 fn m6_5_ctrl_c_sends_sigint() {
-    run_with_pump(
+    let Some(sleep) = locate_shell("sleep") else {
+        eprintln!("skipping: sleep not on PATH (set PMACS_TEST_SLEEP to override)");
+        return;
+    };
+    let setup = format!(
         r#"
-            _G.h = pmacs.repl.spawn { argv = { "cat" } }
+            _G.h = pmacs.repl.spawn {{ argv = {{ "{sleep}", "30" }} }}
             _G.sigint_sent = false
             _G.first_seen_running_at = nil
         "#,
+        sleep = sleep.display(),
+    );
+    run_with_pump(
+        &setup,
         r#"
             local h = _G.h
             if not _G.sigint_sent then
@@ -324,13 +332,21 @@ fn m6_5_ctrl_c_sends_sigint() {
 /// The exit marker uses `basename(argv[0])` (so `/usr/bin/cat`
 /// renders as `cat`), leads with `\n` (so a process exiting mid-line
 /// stays readable), and uses symbolic signal names. Verified by
-/// spawning `/bin/false`, which exits with code 1.
+/// spawning `false`, which exits with code 1.
 #[test]
 fn m6_5_exit_marker_uses_basename_with_leading_newline() {
-    run_with_pump(
+    let Some(false_bin) = locate_shell("false") else {
+        eprintln!("skipping: false not on PATH (set PMACS_TEST_FALSE to override)");
+        return;
+    };
+    let setup = format!(
         r#"
-            _G.h = pmacs.repl.spawn { argv = { "/bin/false" } }
+            _G.h = pmacs.repl.spawn {{ argv = {{ "{false_bin}" }} }}
         "#,
+        false_bin = false_bin.display(),
+    );
+    run_with_pump(
+        &setup,
         r#"
             local h = _G.h
             local buf = h:buffer_id()

tests/m6_perf_acceptance.rs

@@ -86,15 +86,13 @@
 //!   `yes` at the M6.6 ingest rate). Both signals fire in the same
 //!   tick, so the choice is purely a measurement-cost decision.
 //!
-//! - **Why we cancel `yes` directly, not a shell.** `pmacs.process.
-//!   signal(_proc_id, "INT")` signals the *spawned PID*. For a
-//!   shell, that's bash itself, not bash's child (which is what
-//!   `find /` would be). Real-terminal SIGINT semantics involve
-//!   foreground-pgrp routing through the PTY layer, which M6.5
-//!   does not implement. A shell-foreground-pgrp aware C-c is M6.5+
-//!   work; for the M6.6 gate, the cleanest measurement is a
-//!   single-process target (`yes`), which catches SIGINT and exits
-//!   directly.
+//! - **Why we cancel `yes` directly, not a shell.** PTY-mode
+//!   `pmacs.process.signal(_proc_id, "INT")` targets the foreground
+//!   process group. For a shell, that group can include the shell's
+//!   current foreground job rather than only the shell process. For
+//!   the M6.6 gate, the cleanest measurement is a single-process
+//!   target (`yes`), so the foreground group contains the producer
+//!   being measured and no shell/job-control policy enters the timing.
 //!
 //! - **Percentile computation.** Sort the latency samples; p99 is
 //!   `samples[(len * 99) / 100]`, matching M5.9c's exact-integer